Protean Hydra enters the battlefield with X +1/+1 counters on it.

If damage would be dealt to Protean Hydra, prevent that damage and remove that many +1/+1 counters from it.

Whenever a +1/+1 counter is removed from Protean Hydra, put two +1/+1 counters on it at the beginning of the next end step.

Constellation — Whenever an enchantment enters the battlefield under your control, you may have Protean Thaumaturge become a copy of another target creature, except it has this ability.